1. Field of the Disclosure
The present disclosure relates to energy storage devices, in particular, energy storage devices configured to provide fast response ancillary services and/or bulk energy storage which may be used with large scale electricity grids.
2. Background of the Disclosure and Description of the Related Art
The electricity power grid has little means of storing energy. Therefore, the amount of electricity generated should instantaneously match demand as closely as possible. Despite efforts to supply the power grid with the electricity that precisely matches the instantaneous demand, the actual power provided to the grid often exceeds or falls short of the actual power demand at any given moment, causing deviations in the frequency, away from the target operating condition, of the alternating current of the electricity grid. There is therefore a need for a system for rapidly absorbing energy from and outputting energy to the grid.
Likewise, due to dramatic changes in the demand for electricity over a typical 24 hour period, it is necessary for a grid operator to dispatch and curtail electricity generation assets to match the changes in demand. The time difference between minimum and maximum demand can be as long 12 hours. Therefore, a bulk energy storage device, being defined as a device which can produce megawatts of power, sufficient for participating in the electricity grid, and can operate for several hours in duration when either consuming or producing electricity, is needed to manage these large swings in electricity demand.